1. Field of the Invention
The present invention relates to a biocompatible material which is useful as a tissue substitute and as a material for forming or coating biomedical devices.
2. Background and Description of the Related Art
Biocompatible materials and/or compositions have many uses in the medical field. Orthopedic surgeons, plastic surgeons and neurosurgeons, for example, frequently utilize substitute materials in their surgical procedures to augment or cement tissue. Bone substitution or augmentation, for example, is often required to repair or replace damaged, diseased, or congenitally absent tissue. The types of cases requiring bone augmentation range from and include trauma, congenital and degenerative diseases (i.e. spinal fusions), and cosmetic applications. Suitable materials for use as synthetic substitutes of muscular-skeletal tissue are preferably easy to apply, pliable, and shapeable, and are able to withstand the stresses, strains and compressive forces associated with the native tissue being replaced.
Biodegradable materials have been developed for use as implantable prostheses, as pastes, and as templates around which the body can regenerate various types of tissue. Polymers which are both biocompatible and resorbable in vivo are known in the art as alternatives to autogenic or allogenic substitutes. These resorbable biocompatible polymers include both natural and synthetic polymers. Natural polymers are typically absorbed by enzymatic degradation in the body, while synthetic resorbable polymers typically degrade by a hydrolytic mechanism. Synthetic resorbable polymers which are typically used to manufacture medical devices include homopolymers such as poly(glycolide), poly(lactide), poly(.epsilon.-caprolactone), poly(trimethylene carbonate) and poly(p-dioxanone) and copolymers such as poly(lactide-co-glycolide), poly(.epsilon.-caprolactone-co-glycolide), and poly(glycolide-co-trimethylene carbonate). The polymers may be statistically random copolymers, segmented copolymers, block copolymers, or graft copolymers or combinations of any of the above.
The substitutes or pastes preferably have properties which allow them to be contoured into the defect site and are biodegradable. It is also preferable that they are capable of sustaining the mechanical stresses in the respective environments in which the bone substitute are placed. It is also preferable that the materials are able to integrate into surrounding tissues and become substantially vascularized. Inability to accept vascular ingrowth may increase the risk for infection. If infected, the materials must be removed in order to avoid further systemic infection.